GLbyte definition in ARM systems causes problems in GLAbstraction and GLVisualize

[vvjn]

So I'm using the Nvidia Jetson TX2 to run GLVisualize and I came across this method ambiguity error when running the following function in GLAbstraction.jl

gluniform(location::Integer, x::Union{GLubyte, GLushort, GLuint}) 	 = glUniform1ui(GLint(location), x)
gluniform(location::Integer, x::Union{GLbyte, GLshort, GLint, Bool}) = glUniform1i(GLint(location),  x)

The ambiguity is at gluniform(::Integer, x::UInt8), since on the Jetson, both GLbyte and GLubyte maps to UInt8.

This is because Cchar (and thus, ModernGL.GLbyte) maps to UInt8 in the Jetson, while in x86 computers, Cchar maps to Int8. I fixed in the Jetson by defining ModernGL.GLbyte as Int8 in the Jetson. Also before fixing this, GLVisualize had issues rendering colors properly, but after this fix, the colors render properly. I'm not completely sure why this is happening, but ModernGL.GLbyte probably needs to be more consistently defined across architectures.

[r3tex]

Wow, incredible find! Now we can use Makie on the Jetson TX2 and it's fast.